Typical end closures for beer and beverage containers have an opening panel and an attached leverage tab for pushing the opening panel into the container to open the end. The container is typically a drawn and ironed metal can, usually constructed from a thin plate of aluminum or steel. End closures for such containers are also typically constructed from a cutedge of thin plate of aluminum, formed into a blank end, and manufactured into a finished end by a process often referred to as end conversion. These ends are formed in the process of first forming a cutedge of thin metal, forming a blank end from the cutedge, and converting the blank into an end closure which may be seamed onto a container.
These types of container ends have been used for many years, with almost all such ends in use today being the “ecology” or “stay-on-tab” (“SOT”) ends in which the tab remains attached to the end after a tear panel, including large-opening ends (“LOE”), is opened. The tear panel being a portion of the can end defined by a score length. The tear panel may be opened, that is the score may be severed, and the tear panel displaced at an angular orientation relative to the remaining portion of the can end. The tear panel remains hingeably connected to the remaining portion of the can end by a hinge segment, leaving an opening through which the user draws the contents of the container. In an LOE, the opening is at least 0.5 square inches in area.
Opening of the tear panel is operated by the tab which is attached to the can end by a rivet. The tab is attached to the can end such that a nose of the tab extends over a proximal portion of the tear panel. A lift end of the tab is located opposite the tab nose and provides access for a user to lift the lift end, such as with the user's finger, to force the nose against the proximal portion of the tear panel.
When the tab nose is forced against the tear panel, the score initially ruptures at a vent region of the score. This initial rupture of the score is primarily caused by the lifting force on the tab resulting in lifting of a central region of the can end, immediately adjacent the rivet. As the tab is lifted further, the score rupture propagates along the length of the score, eventually stopping at the hinge segment.
Tabs are often also used to convey information to users. This information may be in the form of promotional materials, logos, or the like. Methods such as printing, incising, laser ablation, stamping, etc. have been employed to provide information on the tabs. To date, none of these methods has been widely accepted.
However, laser marking to selectively remove coatings on the tab is becoming increasingly popular. This type of laser marking is particularly popular in branding or creating brand awareness. Here, a beverage company's trademark is laser marked on an enclosed portion of a central webbing of the tab, typically by selectively removing an epoxy coating on the tab.
One problem to overcome in successfully implementing a laser marking system of this type is the very small amount of time, called a dwell time, allowed for the marking. Dwell times are generally less than 100 milliseconds, typically less than 50 milliseconds, and more specifically about 40 milliseconds. The logo, trademark, or symbol must be marked by the laser on the tab during the dwell time and not exceed the dwell time. To produce the symbol within the dwell time, manufacturers use a raster technique with their laser equipment. This presents a second problem, namely resolution or quality of the resulting image.
It is important to any trademark owner that its mark be used properly and reproduced faithfully. Companies expend vast resources on branding and proper trademark usage. Quality variables such as location, resolution, contrast, etc. are closely monitored and adherence to the trademark owners' quality standards is of the utmost importance.
Often times, the trademark usage standards conflict with the necessity to reproduce the trademark during the dwell time.
Many publications are devoted to reproducing symbols and the like on beverage containers. These include: U.S. Patent Application Publication No. 2011/0084051, U.S. Pat. No. 6,080,958, U.S. Pat. No. 6,706,995, U.S. Pat. No. 6,433,302, U.S. Pat. No. 6,498,318, U.S. Pat. No. 6,501,046, U.S. Patent Application Publication No. 2005/0045637, U.S. Pat. No. 6,808,351, U.S. Patent Application Publication No. 2003/0178397, U.S. Pat. No. 6,476,349, U.S. Pat. No. 6,479,787, U.S. Patent Application Publication No. 2006/0151501, U.S. Patent Application Publication No. 2010/0193519, U.S. Pat. No. 6,926,487, U.S. Pat. No. 5,855,969, U.S. Patent Application Publication No. 2011/0226636, U.S. Pat. No. 6,872,913, International Publication No. WO 98/10945, International Publication No. WO 01/51295, International Publication No. WO 2007/007102, and European Patent Publication No. EP 1218248. Co-pending and commonly assigned U.S. application Ser. Nos. 12/363,696 and 12/727,873 and International Patent Application No. PCT/US2011/027942 describe methods of decorating and/or strengthening can end tabs. None of these references adequately addresses the problems set forth above.
Accordingly, the present invention is provided to solve the problems discussed above and other problems, and to provide advantages and aspects not provided by prior laser etched tabs of this type. A full discussion of the features and advantages of the present invention is deferred to the following detailed description, which proceeds with reference to the accompanying drawings.